Memristors advance

The challenge of keeping Moore's Law rolling as semiconductor linewidths dip to 20nm (only about eighty copper atoms wide) has driven such key new process technologies as nanoimprint lithography and EUV optical lithography.  It has also driven quite a few nanopositioning developments, such as positioners capable of picometer resolution plus high holding forces and active vibration isolation systems which provide nanoscale-stable worksurfaces and foundations-- essential enablers for today's most advanced process tools.

But it is also driving development of fundamentally new materials and technologies.  Graphene, a planar cousin to carbon nanotubes and buckyballs, is one of these, and is showing great promise for devising denser and faster microelectronics.

And then there are memristors, announced two years ago by HP and predicted in theory almost four decades ago by Prof. Raymond Chua of the University of California.  Coverage in the IEEE Spectrum journal was particularly informative and is the source of the following two images.

First, these astonishing nanoscale devices are regarded as no less than the fourth fundamental passive electronic component (after resistors, capacitors and inductors): 

Memristors are like resistors with memory.  Think of them as nanoscale potentiometers that can be reversibly set and read in conventional binary 0/1 ways but which are also capable of achieving and maintaining "in between" states.  Thus a single memristor only a few nanometers in extent can conceivably store many bits' worth of information, inviting a significant change in microelectronic architecture.

This means many things, most obviously some serious new competition for flash RAM and hard disks in the near future.  Now Nature reports that these devices have been demonstrated as building-blocks for logic circuitry as well.  Tantalizing recent developments by researcher R. Stanley Williams and colleagues are summarized in a recent IEEE Spectrum article,

The component’s use in computer memory was a foregone conclusion. The memristor can reversibly change its resistance depending on how much current flows through it. The researchers’ surprising new discovery is that a memristor can handle either data storage or logical computation depending on the amount and duration of the current sent through it. Three memristors can complete a NAND operation, the researchers report, so any Boolean function can be implemented if you string enough of the devices together.

Clearly, memristors herald a new chapter in semiconductor engineering, applications and fabrication techniques.  But might there be applications beyond the microchip?  A key purpose of this blog is to bring novel technologies to the attention of our diverse customer base in hopes of spurring cross-pollination and recombinant innovation across multiple fields.  Perhaps memristors will play a role in enabling something entirely new: maybe a novel lab-on-a-chip, or miniaturized autonomous dataloggers powered by piezo scavenginghttp://www.pi-usa.us/pdf/PI_Catalog_DuraAct_Piezo_Patch_Transducer_Piezo_Composite_C1.pdf, or nanoprobes with onboard signal processing and storage.  More likely, it will be none of these-- who, at the birth of the any of the other three fundamental passive circuit elements, could have predicted the computer you're reading this on?

Williams is featured in a fascinating and disarmingly casual online video describing memristors, below.